The present invention relates to a pump for supplying a fluid, in particular hydraulic oil, comprising a drive shaft extending into the interior of the pump and mounted on at least one bearing device lubricated by a leakage flow of fluid, and a sealing device sealing the gap between the housing of the pump and the drive shaft.
Pumps of the type described here, in particular hydraulic pumps, are known. They are situated above an oil sump, for example, of an automatic gearbox in a motor vehicle. It is not possible to lubricate the bearings of the pumps with grease since the grease is flushed out by the oil spray inside the gearbox. A rotary shaft seal and an oil leakage bore are thus normally provided, the oil leakage bore being arranged in such a way that the bearing of the pump is lubricated with oil during the operation of the pump and that the leaking oil can escape by way of the leakage space. It has been found that when the pump is stopped, oil can escape by way of the bearing device, so that the pump runs empty. This means that oil present in the pump chamber escapes, so that the pump chamber fills with air. As a result of the air present in the pump chamber the starting behavior of the pump is permanently affected.